I sweat a lot when I exercise which can cause my socks to move a lot during exercise, either slipping off the heel or creating tension under my foot causing blisters. These socks eliminate both issues, fitting my feet perfectly and beating sweat along the way. I always wear these socks on longer runs. I got my first pair at a running store as part of a promotion. When this pair wore out after a few years I bought another pair which I still have.